Typically I've used Patagonia mid weight and expedition weight but I've been very impressed this past year with the Sport Hill clothing for a base layer (tends not to get as stinky as the Patagucci). I love the River's West LAW system over the top in warmer fall weather and the regular weight H2P when it's colder. Just remember, you pay for what you get. I haven't personally tried the Under Armor but my girlfriend is very impressed with hers.